Monchron clock, LCD problem, was working

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mulveyr
 
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Monchron clock, LCD problem, was working

Post by mulveyr »

Hi All:

My 13-year-old son just assembled the Monochron, and while it worked initially, we now have it boot up with one beep, but no display. The sequence of events was as follows:

1) After initial assembly, the LCD displayed correctly. After powering off, etc. he reamed out the display board holes slightly as per the instructions to get the 4/40 hardware installed for the standoffs.
2) Upon powering up again ( without the case ) to test it, he thinks he saw some smoke, but wasn't able to identify the source. I see no visible indications of a burned component.

Current behavior is:

1) When the logic & display board are connected, the board will power up with a single beep. The backlight turns on. No change is visible when manipulating the contrast control.
2) Powering up just the logic board without the display we get a single beep.
3) Powering up just the logic board WITHOUT the clock chip we get a sequence of paired beeps.
4) Reinserting the clock chip gives us just a single beep again.

As a secondary potential issue, on the display module I see a pair of pads with solder on them at the C1 location, but there is no capacitor there. I don't know if there was one that might have burned and popped off.

So I'm presuming that there's an issue with the clock chip and/or associated circuit. I see no immediately visible problems. I've attached pics of the boards. Can anyone offer suggestions as to where we might try next?

Thanks!

- Rich
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mulveyr
 
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Re: Monchron clock, LCD problem, was working

Post by mulveyr »

Additional pics:
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Re: Monchron clock, LCD problem, was working

Post by adafruit_support_bill »

The solder on the main board looks pretty good. Can we see the component side and the display header also?

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mulveyr
 
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Re: Monchron clock, LCD problem, was working

Post by mulveyr »

Component side and header pics, as requested:
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Re: Monchron clock, LCD problem, was working

Post by adafruit_support_bill »

It looks like a nice clean build. And I believe that the power-up beep pattern is normal.
he thinks he saw some smoke, but wasn't able to identify the source.
Was there any smell of burning plastic? Usually the smoke is accompanied by a nasty odor.
on the display module I see a pair of pads with solder on them at the C1 location, but there is no capacitor there.
The manufacturer produces several variations of the display and not all components are populated for each one. But if you post a photo of the suspect area we can take a closer look.

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mulveyr
 
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Re: Monchron clock, LCD problem, was working

Post by mulveyr »

adafruit_support_bill wrote:It looks like a nice clean build. And I believe that the power-up beep pattern is normal.
he thinks he saw some smoke, but wasn't able to identify the source.
Was there any smell of burning plastic? Usually the smoke is accompanied by a nasty odor.
on the display module I see a pair of pads with solder on them at the C1 location, but there is no capacitor there.
The manufacturer produces several variations of the display and not all components are populated for each one. But if you post a photo of the suspect area we can take a closer look.
He says he's positive there was smoke, but doesn't recall any odor along with it. I came in a few minutes after the fact and didn't notice any unusual odor from either of the boards.

I took a quick look at the firmware source code, and if I'm interpreting it correctly, I think it issues one startup beep, immediately followed by a second beep if the LCD board is initialized successfully. So perhaps the display board is the culprit?

Attached is a pic of the C1 location on the display board.
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Re: Monchron clock, LCD problem, was working

Post by adafruit_support_bill »

I don't have a Monochron handy at the moment. But I will confirm the normal startup beep pattern when I get back to my lab.

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Re: Monchron clock, LCD problem, was working

Post by mulveyr »

adafruit_support_bill wrote:I don't have a Monochron handy at the moment. But I will confirm the normal startup beep pattern when I get back to my lab.
Hi - were you able to confirm the startup behavior? ( With and without the clock chip, etc. )

Thanks!

- Rich

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Re: Monchron clock, LCD problem, was working

Post by adafruit_support_bill »

Yes. With the RTC installed it beeps just once on startup. If it does not find the chip, it issues a series of double beeps.

I also checked my display, but the board is slightly different from yours. There are a couple of blank component spots, but a direct comparison is not possible. If you did see smoke with no plastic smell, a popped ceramic capacitor could have been the source.

If you contact [email protected] with a link to this thread, we can try replacing the display module for your Monochron.

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mulveyr
 
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Re: Monchron clock, LCD problem, was working

Post by mulveyr »

adafruit_support_bill wrote:Yes. With the RTC installed it beeps just once on startup. If it does not find the chip, it issues a series of double beeps.

I also checked my display, but the board is slightly different from yours. There are a couple of blank component spots, but a direct comparison is not possible. If you did see smoke with no plastic smell, a popped ceramic capacitor could have been the source.

If you contact [email protected] with a link to this thread, we can try replacing the display module for your Monochron.
Excellent - thanks for the help!

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mulveyr
 
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Re: Monchron clock, LCD problem, was working

Post by mulveyr »

adafruit_support_bill wrote:Yes. With the RTC installed it beeps just once on startup. If it does not find the chip, it issues a series of double beeps.

I also checked my display, but the board is slightly different from yours. There are a couple of blank component spots, but a direct comparison is not possible. If you did see smoke with no plastic smell, a popped ceramic capacitor could have been the source.

If you contact [email protected] with a link to this thread, we can try replacing the display module for your Monochron.
On the positive side, the replacement display module showed up very quickly, especially considering that it's a holiday week - thanks!

On the negative side, the replacement module results in exactly the same behavior as the original. :-(

Any suggestions for some additional troubleshooting we can do? I have a scope & multimeter available, so we can dig down deeper as necessary.

Thanks!

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mulveyr
 
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Re: Monchron clock, LCD problem, was working

Post by mulveyr »

Bump - any additional suggestions?

Thanks!

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Re: Monchron clock, LCD problem, was working

Post by adafruit_support_bill »

Sorry for the delay. Still trying to make sense of this one. This is a very clean build & I don't see any suspect solder joints or evidence of any overheated components.

Have you checked the voltages? Are you still getting a solid 5v from the voltage regulator?

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mulveyr
 
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Re: Monchron clock, LCD problem, was working

Post by mulveyr »

adafruit_support_bill wrote:Sorry for the delay. Still trying to make sense of this one. This is a very clean build & I don't see any suspect solder joints or evidence of any overheated components.

Have you checked the voltages? Are you still getting a solid 5v from the voltage regulator?

Well, I'm incredibly embarrassed.

After we got the replacement LCD module and put it into place, in the excitement of trying it out, I don't think we had tried readjusting the contrast. When we went to check the voltages this morning we tweaked the contrast, and the display came right up. Swapping out the original display module shows that it was definitely shot.

So we're all good now with the new display. Thanks for the quick assistance, and we'll remember to go through all of the relevant steps next time. ;-)

- Rich

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Re: Monchron clock, LCD problem, was working

Post by adafruit_support_bill »

Cool! Glad you got it working. :D

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